Command prefixes alter the commands recognised by subsequent SSL_CTX_cmd() calls. For example for files, if the prefix "SSL" is set then command names such as "SSLProtocol", "SSLOptions" etc. are recognised instead of "Protocol" and "Options". Similarly for command lines if the prefix is "--ssl-" then "--ssl-no_tls1_2" is recognised instead of "-no_tls1_2".

If the SSL_CONF_FLAG_CMDLINE flag is set then prefix checks are case sensitive and "-" is the default. In the unlikely even an application explicitly wants to set no prefix it must be explicitly set to "".

If the SSL_CONF_FLAG_FILE flag is set then prefix checks are case insensitive and no prefix is the default.